His life was an American dream that, today, seems be crashing down: John Edwards, the millworker's son who became a U.S. senator and a presidential candidate, has been indicted by a federal grand jury today on criminal charges following an investigation seeking to connect Edwards to an allegedly illegal scheme to cover up his extra-marital affair.

Edwards admitted the affair, with film producer Rielle Hunter, in an exclusive interview with ABC News in August 2008.

"I made a very serious mistake. A mistake that I am responsible for and no one else," he said.

Still, Edwards at the time vigorously denied allegations of a cover-up.

"I have never paid a dime of money to any of the people that are involved," he said. "Nothing has been done at my request. So if the allegation is that somehow I participated in the payment of money, that is a lie. An absolute lie."

But former Edwards campaign aide Andrew Young says Edwards was involved in a very big way.

Young told "20/20" in an exclusive interview last year that he knew of at least $1 million that Edwards himself had devoted to the cover-up.

Young says Hunter and Edwards first met in a chance encounter at New York City's Regency Hotel in February 2006.

"She came up to him at the bar and said, 'In person, you come across as very hot with a lot of energy,' but on TV, you don't -- you come across as very distant. I'm in TV. I can help you with that.' That night they were in the same hotel room together and slept together the first night," Young said.

A few months after the affair allegedly began, the senator helped Hunter land a six-figure deal to produce web videos that aimed to reveal the real John Edwards.

As campaign videographer, Rielle Hunter traveled on the first leg of Edwards' official presidential campaign, from New Hampshire to Nevada. When the campaign returned to Edwards' home base in North Carolina on Dec. 30, 2006, Young said Edwards asked him to make sure his wife, Elizabeth Edwards, and his mistress didn't meet -- but the two women came face to face nonetheless.

That night, Young said, Edwards admitted to his wife that he had had an affair. Elizabeth Edwards, who died of cancer four years later, reacted "violently" to the news, he said.

"Anytime that he would almost be asleep, she would get like an inch from his face and start screaming at him," he said.

Hunter was fired the next day, and Young said he found himself largely shut out of the campaign but assuming a different role in Edwards' life: his sole confidant.

"He and Rielle told me way more than I wanted to know about anything and everything," he said.

In May 2007, Young got a frantic call from Hunter. She was pregnant, she told him, and Edwards was the father.

"She says, 'I need to talk to him right now,' and started cursing, and she threatened to go public if I didn't put them together. I said, 'Well, either somebody's died, or somebody's pregnant.' And she said, 'Well, nobody's died,'" Young recalled.

Young said a desperate Edwards started looking for a way out: He convinced Young, who is married with his own children, to claim paternity of Hunter's child. He tried to shield Hunter's pregnancy from the media by sending Hunter, Young and Young's wife into hiding.

In December 2007, the group began traveling by private jets to luxury hotels on a cross-country game of hide and seek. It was all financed by wealthy Edwards campaign operative Fred Baron, and it was all with Edwards' approval, Young said.

"Maybe he didn't know where [we were going], but he knew about the money. He knew about the methodology and he knew about the sources," he said.

Before his death in October 2008, Fred Baron denied that Edwards was in on the scheme. Baron said the trips were entirely his idea.

Hunter and the Youngs eventually settled at a California mansion, rented by Baron for $20,000 a month.

In February 2007, Hunter gives birth. When Young called Edwards to tell them the news, Young said the senator was very short with him.

"It was bone chilling to me," he said. "He is right in the middle of negotiating with Obama and Hillary [Clinton] for being VP or attorney general -- and that took precedence over his child being born."

In July 2008, Edwards traveled to Los Angeles to raise money for the homeless -- but he was also there to visit his newborn child at a Beverly Hills hotel. What he didn't know was that reporters from The National Enquirer had staked out the hotel.

The Enquirer's Allan Butterfield confronted Edwards at the hotel.

"We said to him, 'Are you here to see Rielle Hunter?'" Butterfield said. "He looked like his world had just passed him by, you know, like 'Oh, I'm done.'"

Young said Edwards called him the next morning.

"He was bawling, he was crying, and he said, "I have, I have been caught. I have been caught,'" Young said.

But three weeks later, in an interview with ABC News, when Edwards admitted the affair, he denied that he was the baby's father.

At that point, Young had publicly declared that he was the father. When asked if he believed that to be true, Edwards said he didn't know.

Young said Edwards' comments made him angry.

"At this point when he was admitting an affair, he could have cleared my name," he said.

Despite Edwards' denials, it was soon known that he was the father. The cover-up was over and federal investigators immediately began to follow the money trail, with Andrew Young a witness to the huge transactions.

Andrew Young said he regrets being part of the latest chapter in the rise and fall of John Edwards.

"I am so sorry for my part in this. I am so sorry for what I did to my family.This is going to be on my tombstone," he said.